1. Field of the Invention
This invention relates in general to gas torches, and in particular to a torch which has cutoff valves which allow the preheat adjusting valves to remain at a desired setting, and also to a torch utilizing a pilot flame to ignite the torch flame.
2. Description of the Prior Art
A typical cutting torch operates with gaseous fuel and oxygen. The typical torch has an adjustable fuel valve for supplying fuel gas to a mixing device at the tip of the torch. The torch has an adjustable oxygen valve for supplying oxygen for mixing with the fuel to create a preheat flame when ignited. The torch also has a cutting oxygen valve which supplies a greater quantity of oxygen to the tip when cutting is desired. This latter valve is operated by a spring biased lever arm mounted to the body of the torch.
In use, the operator will open the fuel valve a small increment and ignite the torch typically by using an external striker which creates a spark. Then the operator will adjust the fuel valve and open the preheat oxygen valve until the desired flame quality is achieved for the preheat. The operator preheats the part with the preheat flame. When he desires to start cutting, the operator depresses the oxygen lever which starts the cutting process.
From time to time the operator will need to lay the torch aside while preparing for additional cutting. When this happens, the operator closes both the oxygen and the fuel valves. He then will repeat the procedure when he desires to start the preheating and cutting again. Lighting the torch in this manner is time consuming because it requires adjustment of the fuel and oxygen valves each time.
U.S. Pat. Nos. 3,255,803, F. Hach, Jr., et al., Jun. 14, 1966, and 3,380,881, F. Hach, Jr., et al., Oct. 25, 1966, disclose a torch which has preheat oxygen and fuel cutoff valves in addition to adjusting valves. The cutoff valves operate between open and closed positions, and allow the adjusting valves to remain at a desired setting. The cutoff valves are actuated by depressing the oxygen lever part way. Also, the torches in these patents have a piezoelectric igniter which is actuated by depressing the cutting oxygen lever. While these patents show a torch that is ignited electrically and allows the preset adjustment to remain on the fuel and gas valves, such torches of this nature have not been in common use.
Another proposed means for igniting a preheat flame is shown in U.S. Pat. No. 4,818,220, S. Kobayashi, Apr. 4, 1989. In that patent, a piezoelectric device ignites fuel gas being supplied to a pilot nozzle to create a pilot flame. The pilot flame then ignites the preheat flame of the torch.